The act of insulting someone's music taste by comparing the music they are playing to remarkably terrible music/bands over and over in an obviously taunting manner. This is usually done by the passenger of a car whose owner is playing music.

"Is this Good Charlotte? This bass line sounds just like the one from that Hawthorne Heights song. "OMG! I love the Click Five's new single!"
"Dude, I was cool enough to drive him home yesterday and he totally started DJ Dissing my new emo-punk mix"